My invention relates to an apparatus for the transfer (reading and/or writing) of data with rotating data storage disks typically including a flexible magnetic disk. More particularly, my invention pertains to such a rotating disk data storage apparatus of the kind having a drive pin movably supported in an eccentric position on a turntable for driving engagement in a slot or opening in a metal made hub of the disk. Still more particularly, my invention deals with an improved support mechanism for the drive pin on the turntable.
The three and a half inch flexible magnetic disk is known (FIGS. 1 and 2) which has a sheet metal hub attached centrally thereto, as described and claimed by U.S. Pat. No. 4,445,157 to Takahashi. The hub has formed therein a central opening of square shape and an eccentric opening of rectangular shape. When loaded in the associated data storage apparatus, or disk drive according to common parlance, the disk has its central hub placed upon a turntable of much smaller diameter than that of the disk. The turntable has a permanent magnet for attracting the disk hub. Erected centrally on the turntable, a spindle engages in the central opening in the disk hub for centering the disk with respect to the turntable. Further a drive pin is disposed eccentrically on the turntable for driving engagement in the eccentric slot in the disk hub, imparting the rotation of the turntable to the disk.
I know two conventional approaches to the problem of how to support the eccentric drive pin on the turntable. One employs a cantilever spring support for the drive pin, as described and claimed by U.S. Pat. No. 4,758,915 to Sakaguchi, which is assigned to the assignee of the instant application. The other uses a spring biased lever, as disclosed in Japanese Unexamined Utility Model Publication No. 62-106347.
According to the cantilever spring approach, the drive pin is mounted directly on the spring for displacement both in an upstream direction of the turntable with respect to its predetermined direction of rotation and in a direction parallel to the axis of the turntable. The slanting attitude of the drive pin is intended to maintain the disk in correct angular relationship to the turntable, whereas the drive pin displacement in a direction parallel to the turntable axis is essential for the establishment of the driving engagement of the drive pin in the eccentric slot in the disk hub. Additionally, the drive pin support spring is designed to permit the drive pin to tilt toward the turntable axis for smooth insertion in the disk hub slot.
Although well calculated to accomplish the purposes for which it is designed, the drive pin support spring is very complex in shape and rather inconveniently large in size. It is, moreover, difficult to construct the spring so as to assure resilient displacement of the drive pin in the required directions to required degrees.
The spring biased lever approach, on the other hand, proposes to mount the drive pin on a support lever which is pivotally supported in an eccentric position on the underside of the turntable and which is biased radially outwardly of the turntable by a wire spring. The support lever itself can be of resilient sheet metal material to permit the displacement of the drive pin in a direction parallel to the axis of the turntable. Such resilient displacement of the drive pin in the two directions, made possible by this prior art device, is very effective for the establishment of the proper driving engagement of the turntable with the disk hub. Additionally, the support lever is far easier of fabrication than the noted drive pin support spring suggested by the Sakaguchi patent above.
I nevertheless object to this spring biased lever approach because, unlike the support spring discussed above, the drive pin support lever did not permit the drive pin to tilt toward the turntable axis, being incapable of torsional deflection. This inability of the drive pin to tilt toward the turntable axis brought about the following inconvenience:
When the flexible magnetic disk is first placed on the turntable, the spindle will infallibly enter the central hole in the disk hub. It is very unlikely, however, that the drive pin enter the eccentric slot in the disk hub immediately upon placement of the disk upon the turntable. Consequently, butting against the drive pin, the disk will rest slantingly on the turntable (FIG. 9). As the turntable is subsequently set into rotation, the drive pin will come into register with the eccentric slot in the disk hub before one complete revolution of the turntable and enter the slot if the drive pin has been tilted toward the turntable axis under the weight of the turntable (FIG. 10).
However, should the drive pin stay upstandingly against the weight of the disk, the edge of the eccentric slot might be caught by the drive pin. Then the drive pin would fail to enter the slot.